The present invention relates generally to shielding of electromagnetic interference (EMI) and radiofrequency interference (RFI). More specifically, the present invention relates to metallization and grounding of electrical cables and connectors to provide electromagnetic shielding from electromagnetic interference, radiofrequency interference, and electrostatic discharge (ESD). As subsequently used herein, “EMI” shall include ESD, RFI, and any other type of electromagnetic emission or effect.
Cables and connectors must be allowed to deliver their signals unimpeded. Unfortunately, cables and connectors for connecting electronic devices and specialized cabling that incorporate passive and active electrical devices in a flexible substrate material (e.g., flexible circuits) are both receptors and emitters of EMI radiation. Impingement of EMI can disrupt the functionality of the cable and connectors, and in some cases may cause electronic failure of the cables. With microprocessor speeds continuing to increase, the creation of EMI is a substantial concern to designers, manufacturers, and owners of electronic equipment.
Conventional cable shielding solutions include flexible conductive braiding, conductive epoxies, and conductive foils or tapes that can be wrapped around the dielectric cladding of the cable to provide shielding. Unfortunately, each of the conventional solutions has various drawbacks. For example, the conductive braiding is costly, the conductive epoxies are also costly and difficult to apply to the cladding, and the conductive foils and tapes must manually be wrapped around the cable body.
A particular problem of convention shielding solutions is leakage at the joint where the cable body shielding and connector attach. Gaps or “slot antennas” at joints or seams that break the continuous nature of the shield is a primary reason why shielding effectiveness degrades.
Current shielded cable solutions can provide shielding effectiveness in the range of 20 dB to 50 dB. Unfortunately, with the higher-speed microprocessor technology that is presently in use (and that is being developed) there is a need to provide consistent integrated designs of enclosures, cables, and connectors in the range of 55 dB or higher.
The above mentioned conventional solutions do not provide a high degree of shielding effectiveness and have high leakage problems (thus causing a loss of shielding effectiveness) and often require the use of manual assembly to apply the shields over the connectors and cables. Accordingly, what is needed are systems and methods which provide adequate EMI shielding to cables and connectors.